1. Field of the Invention
This invention relates to a battery connection plate for connection to battery cells used, for example, in an electric car, a hybrid car or the like.
2. Related Art
In an electric car using an electric motor, a hybrid car using both of an electric car and an internal combustion engine, or the like, generally, a plurality of battery cells of a generally bar-shape, having battery electrodes each with external threads, are arranged parallel in an upstanding condition, and are collectively electrically connected together by this battery connection plate.
This conventional battery connection plate is adapted to be connected to the battery electrodes as described above, and this battery connection plate comprises bus bars having battery electrode connecting portions having through holes for respectively passing the battery electrodes, formed on and projecting respectively from distal ends of the plurality of battery cells, therethrough, and the bus bars serially connect the plurality of battery cells by inserting the battery electrodes into the respective through holes and then by bolt-fastening the battery electrodes to the respective bus bars. This battery connection plate further includes voltage detector, voltage detection terminals which are connected at their one ends to the respective voltage detector, and have at their other ends bus bar connecting portions each of which has a passage hole for the passage of the battery electrode therethrough, and connects the voltage detector to the battery electrode, and is connected to the bus bar, and a plate body.
In the conventional battery connection plate of this construction, each battery electrode is inserted into both of the through hole and the passage hole, and is passed therethrough, and a nut is fastened onto the battery electrode projecting from these holes, and as a result the battery connection plate and the battery cell are mechanically and electrically connected together. In this manner, the plurality of battery cells are serially connected, and at the same time voltage detection elements, connected to the respective voltage detection terminals, are connected to the respective battery cells.
Describing this conventional battery connection plate in further detail, the bus bar connecting portion of the voltage detection terminal is disposed in abutting relation to the plate body, and on the other hand the battery electrode connecting portion of the bus bar is bent into a generally slanting condition to be disposed above the bus bar connecting portion, and can be elastically deformed (see, for example, Japanese Patent Publication No. JP 2004-95380A, FIG. 1).
It seems that there is no problem with the battery connecting means employing the conventional battery connection plate. However, it has the following problems.
Namely, there is a slight variation in the length of the individual battery cells, and as a result there has been a fear that the plate-like bus bar connecting portion, disposed in abutting relation to the plate body, is incompletely connected to the battery electrode.
Therefore, there has been developed a structure (as shown in FIGS. 6 to 8) in which an interconnecting portion z3 is bent into a crank-shape, thereby slightly lifting a bus bar connecting portion z1 of a voltage detection terminal off a bottom surface of a recess z4 formed in a plate body z2, so that a gap z5 for absorbing a length variation of a battery cell is formed between the bottom surface of the recess z4 and the bus bar connecting portion z1. It is noted that a slot 5 is provided between the interconnecting portion Z3 and the bus bar connecting portion Z1.
On the other hand, in this kind of battery connection plate, a complicated wiring pattern is required to be formed by bus bars z6 within a limited space, and therefore even the above structure involves problems.
Namely, there are some cases where the interconnecting portion z3 of the voltage detection terminal is disposed on the direction of extending of the bus bar z6 because of layout. This will be more specifically described with reference to FIG. 6. Namely, in the case where an intermediate portion of the bus bar z6 is extended in a left direction (as indicated by dots-and-dash lines) in FIG. 6, part of the bus bar z6 interferes with the interconnecting portion z3 in pressed relation thereto, so that the interconnecting portion z3 fails to properly operate. In this condition, naturally, the length variation of the battery cell can not be absorbed.
And besides, in battery connection plates today, the layout of bus bars and voltage detection terminals has been extremely complicated, and there has been a fear that the bus bar and the voltage detection terminal interfere with each other.